Polymerization of hydrocarbons



525ML u NJ Qi I J. D. GRENKO Erm. POLYMERIZATION 0F HYDROCARBONS Filed June 1e, 1943 JOHN o. GRENKO LYNN IN ENToRs July 23, 1946.

*III

Patented July 23, 1946 POLYMERIZATION OF HYDRO CARBONS John D. Grenko and Lynn R. Strawn, Port Arthur, Tex., assignors vto The Texas Company, New York, N. Y., a corporation of Delaware Application June 18, 1943, Serial No. 491,320

(Cl. :E60-.666)

`4 Claims.

This invention relates to the polymerization of hydrocarbons such as normally gaseous olens` to produce nap'ntha hydrocarbons useful in the manufacture of motor fuel.

The invention involves polymerizing normally gaseous olens such as propylene and butylene by contact with a solid polymerizing catalyst of th'e alumina-silica gel type and more particularly With a catalyst consisting essentially of a mixture of silica, alumina and zirconia such as described in U. S. Patent No. 2,249,583. More specically the invention involves eifecting the polymerization with this type of catalyst under 4conditions such that a polymer naphtha relatively rich in aromatic constituents is obtained.

In accordance With the invention the feed olefin is subjected to contact with an alumina-silica type catalyst at a temperature Within the range about 580 to 700 F. and under apressure of about 150 pounds per squareA inch gauge o1' under a pressure in the range atmospheric .to 300 pounds per square inch gauge.`

type of catalyst within the temperature range in question the resulting polymer is unexpectedly rich in aromatic constituents.

'I'he above mentioned patent broadly discloses subjecting olens to-contact with a catalyst of the type in question at temperatures ranging from 200 to 650 E'. and under pressuresranging from 400 to 4000 poundsper square inch gauge.

Polymerization of olens such as propylene with naturally occurring and synthetic aluminum silicates has also been described by Frederick H.

. Gayer in an article entitled The catalytic polymerization of propylene, published in Industrial and Engineering Chemistry, October,.1933, pages 1122 to 1127. According to this author activated Floridin and especially a synthetic alumina-onsilica catalyst are active in the polymerization of `Where a high superchargingfrate is employed so asto obtain a large power output Without detona- It has been found that f by effecting the polymerization reaction with this Lil Y 2 tion such as is necessary during take-off. In other Words, during take-off it is desirable to employ a rich mixture and for this purpose a naphtha having a high content of aromatic constituents is preferable to one having a high content of parafnic constituents, the latter being useful Where a lean mixture is employed as in cruising operations.

A modification ofthe present invention involves subjecting feed olens to contact with a fresh, or freshly regenerated silica-alumina gel polymerization catalyst at a moderate temperavture not in excessof about 560 F. underwhich conditions the resulting polymer naphtha has a relatively high content of saturatedv hydrocarbons. The used catalyst preferably after being in contact with olen feed hydrocarbons for not more than about 5 hours under-the aforesaid moderate temperatureconditions is then em,- ployed in a separate operation to effect'polymeri'- ization of feed olefins under more elevatedv temperature conditions so` as to obtain a polymer naphtha which is relatively rich in aromatic constituents. The naphtha products obtained from eachoperation may be separately disposed ofor may be blended all or in part for th'e purpose .of

producingmotor fuelY of predetermined characteristics. l

Co-pending application, Serial No. 493,186, for Polymerization of hydrocarbons, filed on July 2, 1943, by Nelson B. Haskell and Charles J. Randolph, Jr., describes more specifically the polymerization of normally gaseous oleins under moderate temperature conditions with an alumina-silica gel type of catalyst so as to obtain polymer gasoline characterized by having a relatively high content of unsaturated hydrocarbons. 'I'he co-pending application discloses effecting the-reaction at a temperature in the range about 425 to 560 F. during passage of the feed hydrocarbons in gas phase through a contact mass of the catalyst employing a mass,y velocity inthera'nge about 0.25 to 0.55 pound of hydrocarbon feed per pound of catalyst per hour. As there disclosed the catalyst remains in contact with the hydrocarbons undergoing treatment for notlonger than about 5 hours between catalystregenerations.

The present invention vinvolves a distinction since ithas to do with employment of a reaction temperature substantially above 560 F. for the purpose of producing polymer vnaphtha of diiferent character, namely, rich in. aromatic constituents. However,. it is Within the scope Vof this invention to employ a two-stage operation,

the first stage involving the aforementioned In the higher temtained onstream for a substantial period of time lof about five to eight `hours or ranging from a lfew hours up to two or three days, thereafter the catalyst is regenerated in the conventional manner and re-employed in the moderate temperature reaction.

In practicing the process of this invention a `catalyst may be maintained in a fixed bed, or

In such f "case the feed olefin heated to the desired ternbeds, within a reaction zone or zones.

perature is continuously passed through the contact mass maintained at the reaction temperalture, and the iiow of hydrocarbons continued therethrough until the catalyst has become spent. Thereupon the catalyst may be regenerated in situ by the passage therethrough f oxygen-bearing gas so as to remove carbonaceous deposits "upon the catalyst by combustion. Advantageously a plurality of reaction zones are employed particularly Where the aforementioned two-stage operation is employed. In this way when the catalyst inthe low temperature stage has been onstream for 5 hours the feedstream may then be diverted to an adjoining reactor containing `fresh or freshly regenerated catalyst.A `During this period the offstream contact mass is emi ployed for the higher temperature reaction until l such time as it has become substantially spent,

when the feed stream is then diverted to another contact mass which may be partially spent in the low temperature reaction. i The completely spent catalyst is then regenerated and thus placed in condition for employment inthe low temperature The several reaction Zones are thus reaction.

`manifolded together by suitable pipe connections so that any one or more of the reactors i may be taken offstream either for use under difl ferent temperature conditions or for regeneration I ofthe catalyst.

Instead of a fixed bed type of operation a mov- ;able bed type of operation may be employed wherein a body of catalyst movesV gradually `through the reaction zone either counter-currently to or concurrently with a stream of feed hydrocarbons undergoing-treatment. For example, two reaction zones may be employed, the rst being used for the low temperature reac- Ition, while the second is used for the higher temperature reaction. A body'of catalyst moves I through the low temperature reaction Zone and i the catalyst issuing therefrom is conducted to the higher temperature zone. The spent catalyst l issuing from this higher temperature zone is then subjected to regeneration after which it is rel turned for use in the low temperature reaction 1 zone."

Y The latter type of operation is illustrated by means of a iiow diagram` shown in the accom- 1 panying drawing to which reference will now be made for the purpose of further description of theY invention.

i alumina gel catalyst in the form of small granules, particles, pellets or pills, etc.

The catalyst is continually fed into the upper portion of the reactor l through a conduit 5. Provision may be made within the reactor for maintaining the catalyst in the form of one or more beds of desired depth. The catalyst moves slowly and downwardly through the reactor from the bottom of which it is removed through a conduit 6.

Thus, as indicated, the feed hydrocarbon in `this instance ows countercurrently to the downwardly moving body of catalyst. The polymerized hydrocarbons including unreacted hydrocarbons are continuously drawn off from the upper portion of the reactor li through a pipe 'l leading to a fractionator or fractionating unit 6.

Fractionation may be carried out so as to separate the product into a plurality of fractions including a gas fraction removed through a pipe 9, a polymer naphtha fraction through a pipe lo and a heavy hydrocarbon fraction through a pipe l l. The gas rfraction will comprise unreacted olefin hydrocarbons which may be recycled all or in part to the heater 2 or to the reactor 4.

A separate stream of feed olefin which may be of the same character as that previously mentioned is conducted fromY a source not shown through a pipe l'to a heater IB wherein it is heatedv to a temperaturein the range 560l to '700 F. The resulting heated hydrocarbons under a pressure of about 1'50 pounds are passed through a pipe Il to the lower portion of a reactor !8 operating on the same principle as the previously mentioned reactor t.

The used catalyst passing through the pipe 6 to which reference has already been made passes v into the upper portion of the reactor lll and provides the moving bedV or beds of catalyst con-V tained within the reactor Ill.

Y currently through the downwardly moving cata- As indicated in the drawing a stream of feed v olefin such as propylene is .conducted from a I source not shown through a pipe I to a heater 2 wherein it is. raised to a temperature inthe range Vl25to 560 F. and under a pressure of abouty 150 ,predetermined characteristics'.

saturated hydrocarbons, whereas the polymer f naphtha issuing from the fractionator 2@ will be relatively rich in aromatic vconstituents and may be substantially free from saturated hydrocarbon constituents. A gas yfraction may be removed from the fractionator 2i) through a pipe 2l and the olefinic constituents thereof recycled yall or in part to the polymerization reaction.

The polymer naphtha may be drawn olf through a pipe 272 while the heavier hydrocarbons are removed through a pipe 2S.

If desired the polymer naphtha products obtained from the two fractionating units may be drawn off all or in part toa receiver 2@ for the purpose of blending to produce motor fuel of Spent catalyst is drawn yoff continuously from the bottom of the reactor lli through a 'conduit 3o and may be passed to a catalyst regeneration unit 3l from which it can be recycled through a n conduitt? to the reactor ii.

In' the'reactor i8 the charging rate may be maintained so that the massY velocity is within Y. the range about .20 to 1.0 pound'of hydrocarbon feed per pound of catalyst per hour.

While a moving bed catalytic operation is described in connection with the drawing, nevertheless it is also contemplated that other means of employing the catalyst may be utilized, as,

for example, a catalyst in powdered form may be injected into a body of the vaporized hydrocarbons undergoing treatment within the reaction zone.

The catalyst may be used in the presence of a small amount of moisture. For example, it may amount to from a fraction of a per cent to several per cent by weight of the feed.

In a fixed bed type of operation it may be advantageous to condition the catalyst following regeneration and this may be accomplished by passing a stream of feed olen through the contact mass or bed at a temperature substantially below the reaction temperature for a period of about 40 to 60 minutes. For example, the catalyst employed in the low temperature reaction may be conditioned by passing feed oleiins at a temperature in the range 75 to 300 F. through the contact mass for a period of about 1 hour.

In the following examples propylenewas subjected to polymerization by the action of the catalyst of the character described in U. S. Patent No. 2,249,583. Such a catalyst consists essentially of a calcined mixture of a major proportion of precipitated silica and minor proportions of alumina and zirconia having approximately the following composition: 100Si02, 2A1203 and 12Z1'O2.

The reactionwas carried out by continuously passing a stream of the propylene in gas phase through a contact mass of Ithe catalyst maintained at a predetermined reaction temperature.

Example A Tlfp" Thile MV Yield Olefins Aromatics saturates In the foregoing tabulation the temperature represents the average reaction temperature of the contact mass; time refers to the length of time in hours that the contact mass has been onstream; MV represents the mass velocity in pounds of charge per pound of catalyst per hour;

yield represents the weight per cent of the polyi Example B Telbl" Thllf" Mv Yield oiefius Aromatics saturates 34o y, .505 39.2 47 c 5a 423- 1 .841 43. s 51 o 49 652- a 31s 7o. 1 4s 53 1 This example'likewise indicates that temperauts have a relatively high content of saturated hydrocarbons. By increasing the temperature to 652 F., however, the aromatic content of the polymer product is increased to 53%.

The polymer gasoline rich in aromatic constituents which is obtained by employing a reaction temperature ranging from about 560 to 700 F. is characterized by having a CFRM octane number of about 78 to 80. 'Ihe addition of 3 ccs. of TEL raises the octane number to about 87.

Mention has been made of treating propylene, but it will be understood that the feed to the process may comprise a mixture of olefin and non-olefin hydrocarbons such as obtained from refinery sources,

Obviously many modifications and variations of the invention, as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore onlysuch limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for polymerizing propylene which comprises passing propylene through a mass of polymerization catalyst consisting essentially of a calcined mixture of precipitated silica, alumina and zirconia having approximately the composition Si02 2Al203: 12Zr02, said catalyst having been previously exposed for a short time to feed olefin under polymerizing conditions at a temperature of at least about 340 F. and not in excess of about 560 F. maintaining a velocity of flow through the contact mass such that the mass velocity through the catalyst is in the range about .2 to .3 and effecting contact between propylene vapor and catalyst at a temperature of about 580 to 650 F., under a pressure of about X to 300 pounds thereby obtaining a polymer naphtha' containing 40 to 50% and more by weight of aromatic hydrocarbons.

2. A process for .polymerizing propylene .to

Vproduce naphtha rich in aromatics which comprises passing propylene in a continuous stream through a mass of polymerization catalyst consisting essentially of. a calcined mixture of precipitated silica, alumina and zirconia having the approximate composition 100Si02: 2Al203: 12Zr02, said catalyst having been previously subjected to contact for a short time with a stream of propylene gas under polymerizing conditions at a temperature below about 560 F., maintaining the catalyst mass at a temperature of about 580 to 650" F., and under a pressure of about 150 to 300 pounds and maintaining a velocity of flow through the contact mass such that the mass velocity through the catalyst is in the range about 0.2 to 1.0 pound of hydrocarbon feed per pound of catalyst per hour.

3. A continuous process for polymerizing propylene which comprises passing a stream of hot propylene vapor through a reaction zone maintained at about 425 to 560 F., subjecting said' vapor to contact therein with a catalyst consisting essentially of a calcined mixture of precipitated* silica, alumina and zirconia having the approximate composition liOOSiOz: 2Alz03: 12Zr02, removing from the reaction zone an eluent hydrocarbon stream comprising polymer naphtha rich `in saturated hydrocarbons, removing used catalyst from said reaction zone, passing re- .movedoatalystto a separate reaction zone, passing lthrough said .separate reaction zone a. sepa.-

raf'terstream .o f v hotl propylene vapor, eectng Contact between used catalyst and lseid Vseparate stream .of propylene vapor at a temperature of about 580 to .650 F., removing from said sepa.- Arate reaction zone an euent hydrocarbon stream comprising polymer nalohtlnal rich n aromentioned reaction zone.

JOHN D. GRENKO. LYNN R. SIRAWN. 

